[Backport 2.18] Add Normalization token filter docs #8239

_analyzers/token-filters/index.md

@@ -44,7 +44,7 @@ Token filter | Underlying Lucene token filter|  Description
 [`min_hash`]({{site.url}}{{site.baseurl}}/analyzers/token-filters/min-hash/) | [MinHashFilter](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/minhash/MinHashFilter.html) | Uses the [MinHash technique](https://en.wikipedia.org/wiki/MinHash) to estimate document similarity. Performs the following operations on a token stream sequentially: <br> 1. Hashes each token in the stream. <br> 2. Assigns the hashes to buckets, keeping only the smallest hashes of each bucket. <br> 3. Outputs the smallest hash from each bucket as a token stream.
 [`multiplexer`]({{site.url}}{{site.baseurl}}/analyzers/token-filters/multiplexer/) | N/A | Emits multiple tokens at the same position. Runs each token through each of the specified filter lists separately and outputs the results as separate tokens.
 [`ngram`]({{site.url}}{{site.baseurl}}/analyzers/token-filters/ngram/) | [NGramTokenFilter](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/ngram/NGramTokenFilter.html) | Tokenizes the given token into n-grams of lengths between `min_gram` and `max_gram`.
-Normalization | `arabic_normalization`: [ArabicNormalizer](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/ar/ArabicNormalizer.html) <br> `german_normalization`: [GermanNormalizationFilter](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/de/GermanNormalizationFilter.html) <br> `hindi_normalization`: [HindiNormalizer](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/hi/HindiNormalizer.html) <br> `indic_normalization`: [IndicNormalizer](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/in/IndicNormalizer.html) <br> `sorani_normalization`: [SoraniNormalizer](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/ckb/SoraniNormalizer.html) <br> `persian_normalization`: [PersianNormalizer](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/fa/PersianNormalizer.html) <br> `scandinavian_normalization` : [ScandinavianNormalizationFilter](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/miscellaneous/ScandinavianNormalizationFilter.html) <br> `scandinavian_folding`: [ScandinavianFoldingFilter](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/miscellaneous/ScandinavianFoldingFilter.html) <br> `serbian_normalization`: [SerbianNormalizationFilter](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/sr/SerbianNormalizationFilter.html) | Normalizes the characters of one of the listed languages.
+[Normalization]({{site.url}}{{site.baseurl}}/analyzers/token-filters/normalization/) | `arabic_normalization`: [ArabicNormalizer](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/ar/ArabicNormalizer.html) <br> `german_normalization`: [GermanNormalizationFilter](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/de/GermanNormalizationFilter.html) <br> `hindi_normalization`: [HindiNormalizer](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/hi/HindiNormalizer.html) <br> `indic_normalization`: [IndicNormalizer](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/in/IndicNormalizer.html) <br> `sorani_normalization`: [SoraniNormalizer](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/ckb/SoraniNormalizer.html) <br> `persian_normalization`: [PersianNormalizer](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/fa/PersianNormalizer.html) <br> `scandinavian_normalization` : [ScandinavianNormalizationFilter](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/miscellaneous/ScandinavianNormalizationFilter.html) <br> `scandinavian_folding`: [ScandinavianFoldingFilter](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/miscellaneous/ScandinavianFoldingFilter.html) <br> `serbian_normalization`: [SerbianNormalizationFilter](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/sr/SerbianNormalizationFilter.html) | Normalizes the characters of one of the listed languages.
 [`pattern_capture`]({{site.url}}{{site.baseurl}}/analyzers/token-filters/pattern-capture/) | N/A | Generates a token for every capture group in the provided regular expression. Uses [Java regular expression syntax](https://docs.oracle.com/javase/8/docs/api/java/util/regex/Pattern.html).
 `pattern_replace` | N/A | Matches a pattern in the provided regular expression and replaces matching substrings. Uses [Java regular expression syntax](https://docs.oracle.com/javase/8/docs/api/java/util/regex/Pattern.html).
 [`phonetic`]({{site.url}}{{site.baseurl}}/analyzers/token-filters/phonetic/) | N/A | Uses a phonetic encoder to emit a metaphone token for each token in the token stream. Requires installing the `analysis-phonetic` plugin.

_analyzers/token-filters/normalization.md

@@ -0,0 +1,88 @@
+---
+layout: default
+title: Normalization
+parent: Token filters
+nav_order: 300
+---
+
+# Normalization token filter
+
+The `normalization` token filter is designed to adjust and simplify text in a way that reduces variations, particularly variations in special characters. It is primarily used to handle variations in writing by standardizing characters in specific languages.
+
+The following `normalization` token filters are available:
+
+- [arabic_normalization](https://lucene.apache.org/core/8_7_0/analyzers-common/org/apache/lucene/analysis/ar/ArabicNormalizer.html)
+- [german_normalization](https://lucene.apache.org/core/8_7_0/analyzers-common/org/apache/lucene/analysis/de/GermanNormalizationFilter.html)
+- [hindi_normalization](https://lucene.apache.org/core/8_7_0/analyzers-common/org/apache/lucene/analysis/hi/HindiNormalizer.html)
+- [indic_normalization](https://lucene.apache.org/core/8_7_0/analyzers-common/org/apache/lucene/analysis/in/IndicNormalizer.html)
+- [sorani_normalization](https://lucene.apache.org/core/8_7_0/analyzers-common/org/apache/lucene/analysis/ckb/SoraniNormalizer.html)
+- [persian_normalization](https://lucene.apache.org/core/8_7_0/analyzers-common/org/apache/lucene/analysis/fa/PersianNormalizer.html)
+- [scandinavian_normalization](https://lucene.apache.org/core/8_7_0/analyzers-common/org/apache/lucene/analysis/miscellaneous/ScandinavianNormalizationFilter.html)
+- [scandinavian_folding](https://lucene.apache.org/core/8_7_0/analyzers-common/org/apache/lucene/analysis/miscellaneous/ScandinavianFoldingFilter.html)
+- [serbian_normalization](https://lucene.apache.org/core/8_7_0/analyzers-common/org/apache/lucene/analysis/sr/SerbianNormalizationFilter.html)
+
+
+## Example
+
+The following example request creates a new index named `german_normalizer_example` and configures an analyzer with a `german_normalization` filter:
+
+```json
+PUT /german_normalizer_example
+{
+  "settings": {
+    "analysis": {
+      "filter": {
+        "german_normalizer": {
+          "type": "german_normalization"
+        }
+      },
+      "analyzer": {
+        "german_normalizer_analyzer": {
+          "tokenizer": "standard",
+          "filter": [
+            "lowercase", 
+            "german_normalizer"
+          ]
+        }
+      }
+    }
+  }
+}
+```
+{% include copy-curl.html %}
+
+## Generated tokens
+
+Use the following request to examine the tokens generated using the analyzer:
+
+```json
+POST /german_normalizer_example/_analyze
+{
+  "text": "Straße München",
+  "analyzer": "german_normalizer_analyzer"
+}
+```
+{% include copy-curl.html %}
+
+The response contains the generated tokens:
+
+```json
+{
+  "tokens": [
+    {
+      "token": "strasse",
+      "start_offset": 0,
+      "end_offset": 6,
+      "type": "<ALPHANUM>",
+      "position": 0
+    },
+    {
+      "token": "munchen",
+      "start_offset": 7,
+      "end_offset": 14,
+      "type": "<ALPHANUM>",
+      "position": 1
+    }
+  ]
+}
+```